JPS61261109A - Pneumatic tire excellent in traction and brake performance - Google Patents

Abstract

PURPOSE:To aim at enhancing the traction and brake performance of a tire, by forming transverse sipings having one end connected to a peripheral groove and the other end connected to relief holes, in the land section including tandem row blocks consisting of peripheral grooves and transverse grooves, within the center area of the tread of the tire. CONSTITUTION:A tread T is sectioned into a center main groove 1, a pair of main grooves 1' and transverse grooves 2, 2' to form four rows of tandem row blocks B, B', two center rows and both side rows, are formed. In the thus formed blocks 3, 3', semi-blind sipings and sipings S1 are formed with relief holes h1 at the cutting terminal ends of the semicircular sipings S, having a spanning length three to five times as large as the cleavage gap of the sipings S1. Similar relief holes h2, h3 are also formed at the intermediate sections of the sipings S2, S3. With this arrangement, it is possible to eliminate eccentric abrasions and to enhance the traction and brake performance of the tire.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) This specification relates to improvements in block type or rip-block type tread patterns in pneumatic tires, more preferably pneumatic radial tires. The following describes the results of development research on improving traction and braking performance.

The tread pattern of this type of tire is particularly wide.

Weather (so-called all-weather) type tires are often of the block type, and each block is narrow enough that they virtually overlap each other under the ground contact surface during tire load transfer to increase traction exclusively on snow. On the other hand, the block or rib block type tread pattern of general tires also has many similar notches, mainly to increase braking force in wet conditions. This cut is usually called a sipe.

(Prior Art) The tread pattern in which sipes are arranged is well known and there is no need to submit any literature about it, but the normal sipe arrangement is generally a so-called blind type, which is independent of the tread groove consisting of circumferential grooves and lateral grooves. There are two types: a separated type, which spans between the tread grooves that cross the tread land area and partition it, and a semi-blind type, which opens into the tread groove only at one end.

(Problem to be solved by the invention) The problem that this invention suffers from is the last-mentioned half-blind type, but compared to the detachable type, the conventional sipes have a higher tread land area. Although it can be said to be a compromise between blind sipes and blind sipes because of the undesirable point of reducing the rigidity of tires too much, it is insufficient to improve the snow performance of all-weather tires or the wet braking ability of regular tires. In addition, there remains a problem in that uneven wear tends to occur at the tread groove edges where the sipes are open.

Therefore, the present invention overcomes these problems, that is, without causing uneven wear on the tread land area, traction,
The purpose is to improve braking performance.

(Means for Solving the Problem) The above purpose is to provide a tread with a plurality of circumferential grooves extending along the circumference of the tread at least in the central area excluding both side areas, and a tread in a direction that intersects with the circumferential grooves. It has a tread land section including at least one column block group divided by a horizontal groove extending along the width direction of the tread land section, and a large number of tread land sections cut into the tread land section from the circumferential groove to a depth equal to or less than that of the circumferential groove. Advantageously fulfilled by a pneumatic tire with sideways sipes, the sipes having a relief hole of greater width and depth at the end of the cut, which has excellent traction and braking performance. .

This escape hole should be at least 2.5 mm thicker than the sipe cut.
The cutting width should be twice, more preferably 3 to 5 times, the gap between the cuts should be 0.5 Fllm, and the depth of the cuts should be 0.5 to 1.0 times the circumferential depth. However, it is especially desirable when it comes to implementation.

The sipe arrangement of the present invention may not only consist of the hemianopic type specified above, but may also be used in combination with a blind type and/or a detachable type.

Now, FIG. 1 shows an example of a block type tread pattern according to the present invention.
A center main groove 1, a pair of main grooves 1' sandwiching the center main groove 1, and a lateral groove 2.2 that is crank-shaped and extends along the width direction of the tread when shown in a direction that intersects these main grooves 1.1'. ′
The blocks B and B' are divided into four columns, two in the center and one on each side.

The amphibatic grooves 1 and 1' can be of a two-stage zigzag type as shown in the figure, and are circumferential grooves that extend along the periphery of the tread T except for both sides of the tread T, and are recessed from the tread surface together with the lateral grooves 2 and 2'. , therefore in this case all of the column blocks B, B' form the tread land, but the transverse grooves 2,
Even tread patterns that include so-called ribs as tread lands without separation by 2' can still benefit from the invention.

The tread land area, in this example blocks 3 and 3', has a circumferential groove 1.
, 1', and half-blind sipes S cut from the inside corner Q, as well as crank-shaped cut-off sipes sl that bisect each block 3 of the central column block group B, on both sides. Two separation sipes S2+3 are provided to separate each block 3' of the formation block, and at the end of the cut of the half-blind sipe S, a relief hole is bored that is larger than the width and depth of the cut, and It is desirable to make a similar relief hole, h, in the middle position of the separation sipe S2+ 33.

Escape hole, h,, h, is Sipe Sl * S2 +S
About 2.5 times or more of the gap between the cuts in 3, especially 3 to 5
Generally, this cut is about 0.5IIIIII wide, so around 2III1φ is suitable. Although an example of a round hole is shown, the planar shape thereof may be triangular, rectangular, polygonal, etc., regardless of the shape, and therefore the size may be determined by the width.

The depth of the escape hole,h,,h, is,
Under the convention that the depth is equal to or less than the depth of 1', it is suitable to be approximately the same as the leading depth, numerically about 0.5 to 1.0 times. - (Function) The escape hole helps to equalize the rigidity in the width direction along the block sipe due to the sipe cut from the circumferential groove so as to end there, and the sipe of the block under the ground contact surface. In addition to contributing to the avoidance of uneven deformation along the road, the uncut portion of the block ensures rigidity and prevents uneven wear, increasing traction on snow and improving braking force on wet roads.

(Example) The method shown in FIG. 1 was applied to the tread pattern of an all-season tire with Sipe 1655R13.

The reinforcement structure of the test tire was the same as before, and all sipes were 0.5111, including the control tire that did not have an escape hole.
The cutting clearance was 111, and the cutting depth was set to 0.7 times the circumferential groove depth.

The escape hole is a round hole with a hole diameter of 2 m + s, which is approximately the same as the circumferential groove depth, to improve control as well as traction performance on snow.
The braking performance on wet road surfaces was compared, and the results shown in the table below were obtained using an index system, with the control performance being set as 100.

The results shown in the same table were also obtained regarding the occurrence of uneven wear in a 20,000 km actual vehicle driving test.

(Effects of the Invention) According to the present invention, the traction performance on snow and the braking performance on wet road surfaces are improved due to the deformation resistance under the contact surface due to substantially uniform rigidity over almost the entire length of the sipe cut. This is advantageously achieved without causing uneven wear of the tread. 1

[Brief explanation of the drawing]

FIG. 1 is a developed view of the tread pattern. 1.1'...peripheral groove 2,2'...horizontal groove B,
B'...Column block group T...Tread S...Hemiblind sipe h...
・Escape hole

Claims (1)

[Claims] 1. A plurality of circumferential grooves extending along the periphery of the tread in at least the central region excluding both sides of the tread, and a plurality of circumferential grooves extending along the width direction of the tread in a direction intersecting the circumferential grooves. A pneumatic tire having a tread land section including at least one vertical block group separated by a lateral groove, and a number of lateral sipes cut into the tread land section from the circumferential groove to a depth equal to or less than that of the circumferential groove. A pneumatic tire with excellent traction and braking performance, characterized in that the sipe has a relief hole with a larger width and depth at the end of the cut. 2. The escape hole is at least 2.
The width is 5 times, more preferably 3 to 5 times,
The tire described in 1. 3. The tire according to 2, wherein the cut depth is 0.5 to 1.0 times the circumferential groove depth.